It is often necessary to track the location of an aircraft or other object in flight. This tracking may occur through use of a portable tracking system in a remote locale. Many tracking applications require an antenna system capable of scanning 360° in azimuth, i.e., a horizontal scan. Typically, a rotatable antenna utilizing a rotary joint or slip ring is employed, wherein a waveguide feed is rotated along with the antenna. Rotary joints and slip rings have been known to be unreliable, especially where the rotational speed of the antenna is substantial and where extended periods of continuous use are required. Additionally, rotary joints and slip rings configured for operation at millimeter wave frequencies can be difficult and expensive to manufacture.
When tracking aircraft, single-axis antennas are often limited by the relatively narrow range of degrees above horizontal in which they can effectively track. As an aircraft increases or decreases in altitude or travels closer to or further from the antenna, such an antenna may have difficulty continuing to track the aircraft.
As such, a need exists for a rotatable antenna system which avoids the problems associated with a rotary joint or slip ring. A need also exists for a single-axis antenna that can track an aircraft through a larger range of degrees above horizontal. A further need exists for a single-axis antenna having characteristics of a directional antenna in azimuth and an omnidirectional antenna in elevation (i.e., vertical) or, in other words, a fan-beam type radiation pattern.